Hydrohistorian
Upper Colorado/Fraser Rivers on the ground — the ditches, wells, reservoirs and gages of Water District 51 · clicktap anything for its record
Snowpack — no snow on the ground at 9 SNOTEL sites — normal for the date; the snow year begins in October and typically peaks around May 3. Runoff outlook — Lake Granby Inflow : even odds of at least 49 kAF over 06-01 to 07-31 — 33% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Runoff outlook — Willow Ck Reservoir Inflow : even odds of at least 7 kAF over 06-01 to 07-31 — 36% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Runoff outlook — Williams Fk bl Williams Fk Reservoir: even odds of at least 10 kAF over 06-01 to 07-31 — 18% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Full snow & runoff picture — charts, forecast history and how the forecasts have verified →
Sites, exceedance bands and sources
| SNOTEL site | Elev (ft) | SWE (in) | Median (in) | % of median | Typical peak |
|---|---|---|---|---|---|
| Berthoud Summit | 11300 | 0.0 | 0.0 | — | May 3 (23.2 in) |
| Fool Creek | 11130 | 0.0 | — | — | — |
| High Lonesome | 10630 | 0.0 | — | — | — |
| Jones Pass | 10430 | 0.0 | 0.0 | — | April 27 (16.8 in) |
| Lake Irene | 10680 | 0.1 | 0.0 | — | April 26 (25.4 in) |
| Middle Fork Camp | 8960 | 0.2 | 0.0 | — | April 4 (11.5 in) |
| Phantom Valley | 9030 | 0.5 | 0.0 | — | March 30 (10.4 in) |
| Stillwater Creek | 8760 | 0.0 | — | — | — |
| Willow Creek Pass | 9520 | 0.5 | 0.0 | — | May 3 (16.4 in) |
Lake Granby Inflow — 06-01 to 07-31 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 27 | 40 | 49 | 58 | 71 | 149 |
Willow Ck Reservoir Inflow — 06-01 to 07-31 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 2 | 5 | 7 | 10 | 15 | 19 |
Williams Fk bl Williams Fk Reservoir — 06-01 to 07-31 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 5 | 8 | 10 | 14 | 20 | 59 |
Snow-water equivalent and medians (1991–2020) from NRCS SNOTEL; seasonal volume forecasts from the NRCS National Water and Climate Center. Sites and forecast points are assigned to the district whose boundary contains them — snowpack that feeds this district can also sit in a neighboring headwater district. Toggle the Snow chip on the map above to see the sites.
Topology cross-check: 7 parent disagreements, 20 sizable streams not on this network (vs DWR's route framework — under review)
This flow network was built mechanically; DWR's Source Water Route Framework disagrees with it in the places below. Each row is a question a human reviewer has not yet answered — not an error verdict. Checked 27 streams, 20 agree. Know this water? Tell us →
| Stream | This site routes it to | DWR routes it to |
|---|---|---|
| Battle Creek | the mainstem | Williams Fork |
| Willow Creek | the mainstem | Little Muddy Creek |
| Smith Creek | the mainstem | Corral Creek |
| Pole Creek | Crooked Creek | Colorado River |
| Tenmile Creek | the mainstem | Fraser River |
| Crooked Creek | the mainstem | Fraser River |
| Hamilton Creek | the mainstem | Hurd Creek |
Sizable streams DWR maps here that this network does not carry:
Arapaho Creek (16 mi) · North Inlet (16 mi) · Little Muddy Creek (13 mi) · Beaver Creek (13 mi) · Onahu Creek (9 mi) · Kinney Creek (8 mi) · Drowsy Water Creek (8 mi) · Reeder Creek (8 mi)
Full diagnostic snapshot pending — this district's weekly-style report (system status, active calls, hydrographs, anomaly flags) is produced by the nightly rotation and appears here after its first run. The tabs above are live now.
Schematic
Historical
Evolution of the network
Trends
This year, in context
In the weeks around 2026-07-06 (the newest reading on file), flows at the 31 ranked gages are running at a median 31% of their own long-term norm for this window — 28 below a typical year, 3 at or above. Driest relative to its record: WILLIAMS FORK NEAR PARSHALL, CO, ranking 1st lowest of 113 years.
How this comparison is made
Each gage's mean flow over the 3 days either side of 2026-07-06, compared with the same window in every year of its own record — so a gage is only ever measured against itself, and gages with no record in the window are counted out rather than guessed.
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-08-30 20:24 from 84 gage(s) with cached period-of-record data. The series is each gage's annual mean flow in cfs (years with ≥300 days of record). Mann-Kendall (trend, with the Hamed–Rao correction for serial correlation — persistence can otherwise fake significance) and Pettitt (changepoint) both require at least 8 years spanning at least 10 years of record. A gage below that reports no signal — which is not the same as “no change.” The %-per-decade figure is the same Sen slope divided by the gage's median annual flow, for comparing across streams of very different size; it is omitted for near-ephemeral channels where the median is too small to divide by honestly.
Of the 84 gages with enough record, 4 are trending down and 3 up, and 8 carry a detected shift. The clearest is Ranch Creek Ditch near Winter Park, its annual mean flow changing +3.35 cfs per decade (+27.1% of its median annual flow) over 25 years (p=0.0083). The other 74 show no clear signal either way.
| Gage | Trend | Change / decade cfs · % of median annual flow | Significance | Years | Changepoint |
|---|---|---|---|---|---|
|
▸
Ranch Creek Ditch near Winter Park RANCRKCO |
↑ increasing | +3.35 cfs +27.1% | p=0.008 | 25 | ~1973 |
|
▸
Ranch Creek Ditch near Fraser RANDIFCO |
↑ increasing | +6.63 cfs +71.7% | p=0.009 | 18 | ~1954 |
|
▸
Colorado River near Grand Lake COLGRACO |
↓ decreasing | -6.08 cfs -7.7% | p=0.012 | 63 | ~1938 |
|
▸
Williams Fork near Parshall WILPARCO |
↓ decreasing | -4.36 cfs -3.5% | p=0.014 | 111 | ~1952 |
|
▸
Colorado River near Granby COLNGBCO |
↓ decreasing | -52.12 cfs -17.8% | p=0.024 | 21 | — |
|
▸
Colorado River below Lake Granby COLGBYCO |
↑ increasing | +10.40 cfs +22.3% | p=0.024 | 13 | — |
|
▸
St. Louis Creek near Fraser SLOFRACO |
↓ decreasing | -1.47 cfs -6.5% | p=0.048 | 91 | ~1958 |
|
▸
Vasquez Creek at Winter Park VASWINCO |
no clear trend | +0.72 cfs +5.7% | p=0.088 | 91 | ~1992 |
|
▸
Fraser River at Winter Park FRAWINCO |
no clear trend | -1.76 cfs -9.3% | p=0.143 | 115 | ~1936 |
|
▸
Ranch Creek near Fraser RANFRACO |
no clear trend | -0.45 cfs -3.3% | p=0.324 | 91 | ~1952 |
74 other gage(s) show no significant trend or changepoint (not shown).
How the measurement network itself changed
This basin was not always measured the way it is today — the API-era record is dense and recent, the early record sparse. 36 gage(s) and 276 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1976. Every historical claim below is checked against this: long-term shifts that co-move with the growth of the network carry an explicit measurement-evolution caution, and abandonment screens whose idleness begins before the modern reporting era are flagged †.
| Decade | Gages with data (median yr) | Structures reporting (median yr) |
|---|---|---|
| 1900s | 3 | 0 |
| 1910s | 4 | 0 |
| 1920s | 2 | 0 |
| 1930s | 13 | 0 |
| 1940s | 16 | 0 |
| 1950s | 26 | 0 |
| 1960s | 23 | 0 |
| 1970s | 22 | 50 |
| 1980s | 22 | 250 |
| 1990s | 23 | 300 |
| 2000s | 28 | 262 |
| 2010s | 32 | 253 |
| 2020s | 36 | 276 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 10% of 2615 schematic-relevant structures. 0 year(s) clear the 30% coverage gate so far -- the trend activates automatically once qualifying years span a full decade. No action needed; the nightly backfill keeps extending the record.
Reach gain/loss shifts (1950–2026)
Mass-balance kinks computed for every summer month back to 1950 (2481 reach-snapshots) — which reaches gain or lose water, and how that has shifted across decades. Each shift is cross-checked against the observation record above: as more diversions became metered, "unaccounted" water shrinks mechanically, which can masquerade as a hydrologic shift.
- RANCH CREEK NEAR TABERNASH, CO.: reach shifted from -129 cfs to -138 cfs summer mean (more losing, p=0.029, 11 yr) [mountain crystalline canyon: minimal groundwater storage -- large or shifting unaccounted losses here are more consistent with data/measurement issues or unmodeled plumbing than with aquifer exchange]
- WILLIAMS FORK BELOW WILLIAMS FORK RESERVOIR, CO: reach shifted from +137 cfs to -146 cfs summer mean (more losing, p=0.000, 73 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=-0.67) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
- WILLOW CREEK BELOW WILLOW CREEK RESERVOIR: reach shifted from -36 cfs to -133 cfs summer mean (more losing, p=0.003, 68 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
Groundwater now has its own tab: 74 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.
Reservoirs now has its own tab: 126 reservoir(s), end-of-year storage back to 1975, click-to-chart histories.
Cross-gage pattern fingerprint
Over the 92-year window with full coverage (1935–2026), the dominant shared pattern across 3 gage(s) explains 76% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).
All gages in this window move with the shared pattern -- no localized outlier.
Structures most implicated by reconciliation (as of 2026-07-06)
Which structures' data absorbed the most correction when the current mass-balance snapshot was reconciled -- see the Historical tab for the full picture on any date.
- WADE REED DITCH (diversion): +4.7 cfs (17% of that reach's correction)
- HENDERSON TUNNEL INTAKE 3 (diversion): +4.7 cfs (17% of that reach's correction)
- GLENMAR DITCH (diversion): +4.7 cfs (17% of that reach's correction)
- REED DITCH (378) (diversion): +4.7 cfs (17% of that reach's correction)
- MARKLE DITCH (diversion): +4.7 cfs (17% of that reach's correction)
- GLENMAR PIPELINE (diversion): +4.7 cfs (17% of that reach's correction)
- HOT SULPHUR SPRINGS WATER SYSTEM (diversion): +3.9 cfs (3% of that reach's correction)
- HOT SULPHUR WATER SYSTEM ALTERNATE POINT (diversion): +3.9 cfs (3% of that reach's correction)
- BOODRY SPRING NO 1 (return): +3.9 cfs (3% of that reach's correction)
- GRAND COUNTY ROAD AND BRIDGE COLORADO RI (diversion): +3.9 cfs (3% of that reach's correction)
Data provenance & quality
Where these numbers come from and how far they can be trusted. Grade D (2/6 points) — the components below are the finding; the letter alone is not. Sources: DWR HydroBase snapshot HydroBase_CO_20260707 (imported 2026-08-19) for history, plus the CDSS REST API for current conditions.
| Check | State | What was measured |
|---|---|---|
| gage freshness | stale | newest gage reading is 55 day(s) old (target 7) |
| diversion record | stale | newest diversion record is 669 day(s) old (DWR publishes ~1 year in arrears) |
| structure coverage | sparse | 10% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 103,104 stored values re-checked against DWR's authoritative record (HydroBase_CO_20260707), over 20 structures. 0 disagreement(s) beyond a 0.01 cfs tolerance. Checked 2026-08-19; a rotating sample covers the whole basin across successive runs, and the structures this report cites are checked every time.
Federal cross-check: PASS — 99.81% day-level agreement with USGS's own published records for the same gages, across 61 co-listed station(s) and 601,272 overlapping days (within max(2%, 0.5 cfs) daily). Pre-1950 records at some gages carry known between-agency day-stamp and transcription differences — scored at each year's best ±1-day alignment; residual disagreement is real historical divergence, flagged for review.
84 gage(s) / 757,491 daily values (1904-10-01–2026-07-06); 628 structure(s) with diversion records; 2208 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.
Groundwater
1,051 water-level measurements across 74 monitored well(s) — 65 alluvial, 0 bedrock — plus 19 administered well(s) reporting metered pumping.
What is being counted
Observation wells and pumping wells are different populations and are never conflated: water levels come from monitored observation wells, and metered pumping comes from administered wells reporting through diversion records. Click any well to chart its own record.
Well map
3D aquifer x-ray
Every aquifer unit as its own head surface, animated through time.
How the surfaces are built, and what they are not
Alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured, interpolated from measured water levels. Units are never mixed; a surface exists only inside its own unit's well coverage, with no extrapolation; thin epochs are suppressed and say why. Vertical scale is exaggerated for readability and z is head elevation in feet. These are measured heads, not a calibrated groundwater model.
Water-table trends
Of 0 well(s) with enough record for a trend test: 0 declining, 0 rising.
Stream corridors — the surface connection
Where a reach's gain or loss has shifted, the wells within two miles of its anchoring gage and what their water table did over the same era.
How the corridor is assembled
For each reach whose gain/loss has shifted (Trends tab): the wells within 2 miles of its anchoring gage, their pooled water-table history over the same era, and an advisory Glover screen of lagged stream depletion from nearby metered pumping. v1 proximity = distance to the reach's anchoring gage; segment-based reach join is a flagged upgrade.
RANCH CREEK NEAR TABERNASH, CO.: 1 alluvial well(s) nearby; pooled water table — ft (1996–2011, no_trend, p=0.7105)
Wells labeled by administrative world before anything else is said about them: tributary alluvium participates in the priority system; designated-basin and Denver Basin bedrock aquifers are governed differently and are excluded from stream-connection reasoning. Read bedrock declines differently too: deep bedrock aquifers recharge negligibly on human timescales, so a falling bedrock level is storage mining — effectively permanent — not a drought response that a wet year undoes. All screens advisory.
Reservoirs
126 reservoir(s) with 11,152 storage measurement(s), 1975–2025. Basin storage as of 2024-10-31 (the record's own end — reservoir records publish ~annually): 569,595 AF across 33 reservoir(s).
Why storage matters to the flow network
Storage change is real water the mass balance must credit — a losing reach beside a filling reservoir isn't losing water, it's banking it.
Reservoir map — how full is each vessel?
What “full” is measured against
Bubble size is proportional to a reservoir's record-high storage. Fill is its last recorded storage as a share of its surveyed capacity (USACE National Inventory of Dams) where a confident NID match exists — the tooltip names the matched dam — and as a share of its own record high otherwise. A wrong capacity would be worse than an honest record high, so only confident joins upgrade.
A dashed teal ring marks reservoirs reporting live DWR telemetry: their fill reflects yesterday's storage, is drawn as a dotted tail on charts, and is treated as provisional until the next verified HydroBase snapshot supersedes it.
A dashed red ring marks a dam under an active storage restriction from DWR's Dam Safety branch — the State Engineer has limited how much it may legally store, so a low fill can be an order, not a drought. Hazard class and inspection condition come from the same record, joined only where the dam carries this reservoir's WDID or a confident NID match — a wrong dam's restriction would be worse than none shown.
Basin storage, end of each water year
End-of-water-year totals; per-year reservoir counts shown because reporting coverage varies -- a total is only comparable to years with similar counts.
Largest reservoirs on record
Click a row to chart its full storage history, or open its dossier for rights, documents and dam-safety facts.
| Reservoir | Last recorded storage (AF) | As of | Full | Dam (DWR Dam Safety) | |
|---|---|---|---|---|---|
| ▸ CBT GRANBY RESERVOIR (5104055) | 462,484 | 2024-10-31 | — | — | dossier → |
| ▸ WILLIAMS FORK RESERVOIR (5103709) | 81,431 | 2024-10-31 | — | — | dossier → |
| ▸ CBT SHADOW MOUNTAIN LAKE (5103695) | 16,969 | 2024-10-31 | — | — | dossier → |
| ▸ CBT WILLOW CREEK RESERVOIR (5103710) | 6,970 | 2024-10-31 | — | — | dossier → |
| ▸ EAST BRANCH RESERVOIR (5103715) | 1,738 | 2016-10-31 | — | — | dossier → |
| ▸ MEADOW CREEK RESERVOIR (5103686) | 611 | 2024-10-31 | — | — | dossier → |
| ▸ SYLVAN RESERVOIR (5103701) | 300 | 2024-09-10 | — | — | dossier → |
| ▸ JACK ORR RESERVOIR (5104009) | 245 | 1994-10-31 | — | — | dossier → |
Snow and runoff
Snow-water equivalent, WY2026
No snow on the ground — normal for the date; the snow year begins in October. The chart shows the full water year just ending.
| SNOTEL site | Elev (ft) | SWE (in) | Median (in) | % of median | Typical peak |
|---|---|---|---|---|---|
| Berthoud Summit | 11300 | 0.0 | 0.0 | — | May 3 (23.2 in) |
| Fool Creek | 11130 | 0.0 | — | — | — |
| High Lonesome | 10630 | 0.0 | — | — | — |
| Jones Pass | 10430 | 0.0 | 0.0 | — | April 27 (16.8 in) |
| Lake Irene | 10680 | 0.1 | 0.0 | — | April 26 (25.4 in) |
| Middle Fork Camp | 8960 | 0.2 | 0.0 | — | April 4 (11.5 in) |
| Phantom Valley | 9030 | 0.5 | 0.0 | — | March 30 (10.4 in) |
| Stillwater Creek | 8760 | 0.0 | — | — | — |
| Willow Creek Pass | 9520 | 0.5 | 0.0 | — | May 3 (16.4 in) |
NRCS SNOTEL, daily. Sites are assigned to the district whose boundary contains them — the snow that feeds this district can also sit in a neighboring headwater district.
Two ways a snow year goes wrong (1979–2026)
A bad snow year here comes in two flavors (both called snow droughtA winter that shorts the snowpack. It happens two ways: a dry one, where the snow never comes, and a warm one, where near-normal snow falls but melts off weeks early -- and the river feels them differently.), and the river feels them differently. In 6 of the last 48 winters the snow never came — the pack peaked below 80% of its median. In 0 more, the snow came but left early — a near-normal peak melted out two weeks or more ahead of its usual date, sending the water down before the season needed it. This year was one of the dry ones: the pack peaked at 55% of median.
The snow never came: 1981, 1987, 2002, 2004, 2012, 2026.
Computed by this site from 9 SNOTEL sites’ full daily records (NRCS AWDB, back to 1979). Each year is measured against each site’s own multi-decade median — not the 1991–2020 normal the chart above uses — so the 1980s grade against a fair baseline. Peak and melt-out need 85% of the season’s days on the record; thin years are dropped, not guessed. Derived from snow measurements alone — it cannot tell dry-from-warm causes apart, only what the snowpack did.
Runoff outlook — Lake Granby Inflow
NRCS's final issue (2026-06-01) calls it even odds that at least 49 kAF arrives over 06-01 to 07-31 — 33% of a normal season; almost certainly at least 27, probably not more than 71. Our own record at this gage shows 8 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal | Observed |
|---|---|---|---|---|---|---|
| 27 | 40 | 49 | 58 | 71 | 149 | 8 |
How good are these forecasts here? (2009–2025)
Grading every April issue against what the river then delivered, measured at this gage’s own record — 12 seasons: the median miss of the 50% forecast is 971%, with a high bias of 971%, and the observed volume landed inside the stated 10–90% band 0% of the time (a calibrated forecast would say 80%).
Computed by this site: NRCS's archived April issues (their period as issued each year) against the observed volume in DWR’s published record; years with under 90% daily coverage are dropped, not summed. A grade of the forecast, never of the forecasters — these are hard rivers. How this point ranks among every graded Colorado forecast point →
What April snow has meant for this river (2009–2025)
Across 12 measured years, the season’s water has loosely followed the April snowpack: a year opening April with 80% of median snow has typically gone on to deliver about 92% of a normal season (a snow-to-runoff elasticityHow strongly one number moves with another. A snow-to-runoff elasticity of 1.5 means a 10% shortfall in April snowpack has typically become a 15% shortfall in the season's water. of 1.0).
Computed by this site: the district’s April 1 SWE (% of each SNOTEL site’s own-record median) against the observed April–July volume at this gage (% of its median season) — a fixed window every year, unlike the forecast grades above, which use each issue’s own period. The slope is fit so single wild years can’t steer it (Theil–Sen, log space); years missing 10% of their days are dropped.
Runoff outlook — Willow Ck Reservoir Inflow
NRCS's final issue (2026-06-01) calls it even odds that at least 7 kAF arrives over 06-01 to 07-31 — 36% of a normal season; almost certainly at least 2, probably not more than 15. Our own record at this gage shows 0 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal | Observed |
|---|---|---|---|---|---|---|
| 2 | 5 | 7 | 10 | 15 | 19 | 0 |
How good are these forecasts here? (1954–2025)
Grading every April issue against what the river then delivered, measured at this gage’s own record — 63 seasons: the median miss of the 50% forecast is 339%, with a high bias of 339%, and the observed volume landed inside the stated 10–90% band 11% of the time (a calibrated forecast would say 80%).
Computed by this site: NRCS's archived April issues (their period as issued each year) against the observed volume in DWR’s published record; years with under 90% daily coverage are dropped, not summed. A grade of the forecast, never of the forecasters — these are hard rivers. How this point ranks among every graded Colorado forecast point →
What April snow has meant for this river (1979–2025)
Across 39 measured years, the season’s water has loosely followed the April snowpack: a year opening April with 80% of median snow has typically gone on to deliver about 93% of a normal season (a snow-to-runoff elasticityHow strongly one number moves with another. A snow-to-runoff elasticity of 1.5 means a 10% shortfall in April snowpack has typically become a 15% shortfall in the season's water. of 1.7).
Computed by this site: the district’s April 1 SWE (% of each SNOTEL site’s own-record median) against the observed April–July volume at this gage (% of its median season) — a fixed window every year, unlike the forecast grades above, which use each issue’s own period. The slope is fit so single wild years can’t steer it (Theil–Sen, log space); years missing 10% of their days are dropped.
Runoff outlook — Williams Fk bl Williams Fk Reservoir
NRCS's final issue (2026-06-01) calls it even odds that at least 10 kAF arrives over 06-01 to 07-31 — 18% of a normal season; almost certainly at least 5, probably not more than 20. Our own record at this gage shows 6 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal | Observed |
|---|---|---|---|---|---|---|
| 5 | 8 | 10 | 14 | 20 | 59 | 6 |
How good are these forecasts here? (1993–2025)
Grading every April issue against what the river then delivered, measured at this gage’s own record — 32 seasons: the median miss of the 50% forecast is 140%, with a high bias of 140%, and the observed volume landed inside the stated 10–90% band 16% of the time (a calibrated forecast would say 80%).
Computed by this site: NRCS's archived April issues (their period as issued each year) against the observed volume in DWR’s published record; years with under 90% daily coverage are dropped, not summed. A grade of the forecast, never of the forecasters — these are hard rivers. How this point ranks among every graded Colorado forecast point →
What April snow has meant for this river (1979–2025)
Across 47 measured years, the season’s water has loosely followed the April snowpack: a year opening April with 80% of median snow has typically gone on to deliver about 75% of a normal season (a snow-to-runoff elasticityHow strongly one number moves with another. A snow-to-runoff elasticity of 1.5 means a 10% shortfall in April snowpack has typically become a 15% shortfall in the season's water. of 1.9).
Computed by this site: the district’s April 1 SWE (% of each SNOTEL site’s own-record median) against the observed April–July volume at this gage (% of its median season) — a fixed window every year, unlike the forecast grades above, which use each issue’s own period. The slope is fit so single wild years can’t steer it (Theil–Sen, log space); years missing 10% of their days are dropped.
Legal
Decreed rights on this network run from 1864-06-01 to 2024-11-30. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 33% of a median irrigation season and 0% in a dry one. 25 abandonment screens and 332 compliance flags are listed below as leads for review — a screen is not an abandonment and a flag is not a violation.
Rights on file: 3490 across 2208 structure(s); 375 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.
Is the river getting harder to divert from?
Over 1988–2025, administration on this district has been tightening: 3 of 3 measures (days under call, calls set, seniority of the controlling call) are moving toward more administration, none the other way.
The three measures, year by year
One row per whole calendar year inside the call record's coverage (38 years); partly-covered years are omitted rather than reported as quiet. Trend is Mann-Kendall with the same significance gate as every other trend on this site. Counted from DWR's published call record, which begins in the early 2000s: earlier years are absent, not quiet. A rise in the number of calls set can also reflect how finely an administrator records one episode, which is why days under call -- insensitive to that -- is the component to read first. Advisory summary of the public record, not an administrative finding.
| Year | Days under call | Calls set | Controlling priority (median) |
|---|---|---|---|
| 2014 | 365 | 184 | 1884-04-07 |
| 2015 | 365 | 256 | 1885-07-28 |
| 2016 | 366 | 237 | 1884-04-26 |
| 2017 | 365 | 330 | 1884-05-01 |
| 2018 | 365 | 290 | 1884-03-02 |
| 2019 | 365 | 165 | 1886-08-09 |
| 2020 | 366 | 221 | 1883-03-30 |
| 2021 | 365 | 218 | 1883-03-15 |
| 2022 | 365 | 201 | 1885-06-01 |
| 2023 | 365 | 120 | 1885-07-28 |
| 2024 | 366 | 164 | 1886-08-09 |
| 2025 | 365 | 232 | 1885-06-16 |
Why diversions stopped — call-based explanations
Sustained diversion stops matched to senior administrative calls.
- AXEL DITCH (5100513) DWR↗ stopped 2024-08-03 (64+ days) — call at CAMP BIRD DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BERG NO 1 DITCH (UPSTREAM) (5100525) DWR↗ stopped 2024-07-19 (67+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BERG NO 2 DITCH (DOWNSTREAM) (5100526) DWR↗ stopped 2024-07-19 (67+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BRINKER DITCH (5100539) DWR↗ stopped 2024-07-14 (45+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- ALEXANDER DITCH (5100503) DWR↗ stopped 2024-07-13 (34+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BUEHLER NO 2 DITCH (5100542) DWR↗ stopped 2024-07-10 (76+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BUEHLER NO 3 DITCH (5100543) DWR↗ stopped 2024-07-10 (76+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BUEHLER NO 4 DITCH (5100544) DWR↗ stopped 2024-07-10 (76+ days) — call at EAST DIVIDE CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BECK DITCH (5100521) DWR↗ stopped 2024-07-08 (72+ days) — call at ATKINSON DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BARKER NO 1 DITCH (5100516) DWR↗ stopped 2023-10-30 (214+ days) — call at MOCKING BIRD DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BEAVER DAM DITCH (5100520) DWR↗ stopped 2023-09-28 (255+ days) — call at ATKINSON DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BRINKER DITCH (5100539) DWR↗ stopped 2023-09-27 (230+ days) — call at MOCKING BIRD DITCH curtailing 100% of its decreed rate [heuristic-strong]
Right yield — how often could these rights actually divert?
Share of irrigation-season days each structure's rights were not called out, derived from the 22-year district-scoped call record (senior right = floor, junior right = ceiling constraint). Call-record-derived; DWR's own analysis governs where available.
| Structure | Senior priority | Senior right: median / dry yr | Junior right: median / dry yr |
|---|---|---|---|
| CBT GRANBY PUMP CANAL (5100678) DWR↗ | 1935-08-01 | 33.2% / 0.0% | 33.2% / 0.0% |
| MOFFAT WATER TUNNEL (5104655) DWR↗ | 1921-07-04 | 33.2% / 0.0% | 33.2% / 0.0% |
| WINDY GAP PUMP PIPELINE CANAL (5104700) DWR↗ | 1967-06-22 | 9.8% / 0.0% | 9.8% / 0.0% |
| CBT ALVA B ADAMS TUNNEL (5104634) DWR↗ | 1935-08-01 | 33.2% / 0.0% | 33.2% / 0.0% |
| GRAND RIVER DITCH (5104601) DWR↗ | 1890-09-01 | 100.0% / 0.0% | 100.0% / 0.0% |
| CBT WILLOW CREEK FEEDER (5100958) DWR↗ | 1935-08-01 | 33.2% / 0.0% | 33.2% / 0.0% |
| WILLIAMS FORK POWER CONDUIT (5101237) DWR↗ | 1933-10-15 | 33.2% / 0.0% | 9.8% / 0.0% |
| FRASER RIVER DIVERSION PROJECT - FRASER (5100639) DWR↗ | 1921-07-04 | 33.2% / 0.0% | 5.6% / 0.0% |
| WILLIAMS FORK TUNNEL (5104603) DWR↗ | 1921-07-04 | 33.2% / 0.0% | 33.2% / 0.0% |
| BIG LAKE DITCH (5100529) DWR↗ | 1903-02-06 | 100.0% / 0.0% | 5.6% / 0.0% |
| FRASER RIVER DIVERSION PROJECT - VASQUEZ (5101310) DWR↗ | 1921-07-04 | 33.2% / 0.0% | 5.6% / 0.0% |
| RED TOP VALLEY DITCH (5100848) DWR↗ | 1901-11-10 | 100.0% / 0.0% | 5.6% / 0.0% |
Abandonment radar (25 screens)
Absolute rights with 10+ years of no recorded diversions. Screens only — storage, alternate points, and plan operations can explain nonuse lawfully. And diversion REPORTING itself only reached its modern level ~1976 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- GRAND LAKE PIPELINE (5100679) DWR↗ (1945-03-15, 6.0 cfs decreed): last active 1976 — 35 years idle
- HOLZWARTH DITCH NO 3 (5100713) DWR↗ (1920-06-01, 1.0 cfs decreed): last active 1976 — 35 years idle
- KIMSEY NO 1 DITCH (5100762) DWR↗ (1891-05-01, 1.6 cfs decreed): last active 1976 — 35 years idle
- MILLS GULCH DITCH (5100797) DWR↗ (1864-06-01, 0.5 cfs decreed): last active 1976 — 35 years idle
- WOOD PIPELINE (5100969) DWR↗ (1931-01-01, 0.0 cfs decreed): last active 1976 — 35 years idle
- BUNTE RESERVOIR (5103646) DWR↗ (1911-04-18, 0.0 cfs decreed): last active 1976 — 35 years idle
- F W LINKE RESERVOIR (5103659) DWR↗ (1948-05-13, 0.0 cfs decreed): last active 1976 — 35 years idle
- F W LINKE NO 2 RESERVOIR (5103660) DWR↗ (1950-10-11, 0.0 cfs decreed): last active 1976 — 35 years idle
- HANKINSON RESERVOIR (5103665) DWR↗ (1949-01-27, 0.0 cfs decreed): last active 1976 — 35 years idle
- LINKE RESERVOIR (5103680) DWR↗ (1910-10-20, 0.0 cfs decreed): last active 1976 — 35 years idle
Compliance screens (332 advisory flags)
Screened 442 of 2208 structures with rights (526 have diversion history on file). A flag is a lead for expert review — augmentation plans, exchanges, and free-river conditions can make over-decree diversions lawful and are deliberately not modeled.
- CBT WILLOW CREEK FEEDER (5100958) DWR↗: Observed p99 daily rate 444.0 cfs (max 551.0) exceeds total decreed absolute 400.0 cfs across 36486 recorded day(s).
- KINNEY BARRIGER DITCH (5100763) DWR↗: Observed p99 daily rate 96.1 cfs (max 114.0) exceeds total decreed absolute 65.0 cfs across 12282 recorded day(s).
- RED TOP VALLEY DITCH - STILLWATER CREEK (5101315) DWR↗: Observed p99 daily rate 92.0 cfs (max 120.0) exceeds total decreed absolute 12.0 cfs across 3495 recorded day(s).
- FRASER RIVER DIVERSION PROJECT - LITTLE (5101265) DWR↗: Observed p99 daily rate 60.0 cfs (max 107.0) exceeds total decreed absolute 0.7 cfs across 8394 recorded day(s).
- BUNTE HIGHLINE DITCH (5100546) DWR↗: Observed p99 daily rate 50.0 cfs (max 54.0) exceeds total decreed absolute 45.0 cfs across 9915 recorded day(s).
- SOPHRONIA DAY DITCH (5100893) DWR↗: Observed p99 daily rate 40.5 cfs (max 48.2) exceeds total decreed absolute 24.1 cfs across 8932 recorded day(s).
- OSTRANDER DITCH (5100826) DWR↗: Observed p99 daily rate 31.0 cfs (max 32.1) exceeds total decreed absolute 16.0 cfs across 7031 recorded day(s).
- HAMILTON-CABIN CREEK EXTENSION (5101250) DWR↗: Observed p99 daily rate 29.0 cfs (max 63.0) exceeds total decreed absolute 25.0 cfs across 24685 recorded day(s).
- MUSGRAVE DITCH (5100810) DWR↗: Observed p99 daily rate 27.8 cfs (max 50.5) exceeds total decreed absolute 25.0 cfs across 17386 recorded day(s).
- SHERIFF DITCH (COLORADO RIVER) (5100883) DWR↗: Observed p99 daily rate 25.4 cfs (max 25.4) exceeds total decreed absolute 18.8 cfs across 6849 recorded day(s).
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| CBT GRANBY PUMP CANAL (5100678) DWR↗ | 1935-08-01 | 1 | 1100.0 | 0 | — |
| MOFFAT WATER TUNNEL (5104655) DWR↗ | 1921-07-04 | 1 | 928.0 | 0 | yes |
| WINDY GAP PUMP PIPELINE CANAL (5104700) DWR↗ | 1967-06-22 | 3 | 600.0 | 0 | — |
| CBT ALVA B ADAMS TUNNEL (5104634) DWR↗ | 1935-08-01 | 1 | 550.0 | 0 | — |
| GRAND RIVER DITCH (5104601) DWR↗ | 1890-09-01 | 1 | 524.6 | 0 | — |
| CBT WILLOW CREEK FEEDER (5100958) DWR↗ | 1935-08-01 | 1 | 400.0 | 0 | — |
| WILLIAMS FORK POWER CONDUIT (5101237) DWR↗ | 1933-10-15 | 3 | 311.0 | 0 | yes |
| FRASER RIVER DIVERSION PROJECT - FRASER (5100639) DWR↗ | 1921-07-04 | 6 | 275.7 | 0 | yes |
| WILLIAMS FORK TUNNEL (5104603) DWR↗ | 1921-07-04 | 1 | 254.0 | 0 | yes |
| BIG LAKE DITCH (5100529) DWR↗ | 1903-02-06 | 3 | 231.0 | 0 | yes |
| FRASER RIVER DIVERSION PROJECT - VASQUEZ (5101310) DWR↗ | 1921-07-04 | 6 | 175.0 | 0 | yes |
| RED TOP VALLEY DITCH (5100848) DWR↗ | 1901-11-10 | 2 | 150.0 | 0 | yes |
| MIN FLOW COLORADO RIVER TROUBLESOME-BLUE (5102036) DWR↗ | 1980-07-08 | 1 | 150.0 | 0 | — |
| MIN FLOW COLORADO RIVER WILLIAMS FK-TROU (5102037) DWR↗ | 1980-07-08 | 1 | 135.0 | 0 | — |
| WILLIAMS FORK DIVERSION PROJECT - SOUTH (5101279) DWR↗ | 1921-07-04 | 3 | 115.0 | 0 | yes |
No inventory or legal-document changes detected since the daily watch began.
Water-court filings this month (division-wide)
1 application in the 2026-08 resume for this basin's division — new rights, changes, augmentation plans — from the water clerk's statutory monthly notice (C.R.S. 37-92-302), the earliest public signal of a new claim. Filings are division-wide, not district-filtered: check the county column. Full resume PDF at the Judicial Branch →
Anyone affected may file a statement of opposition until 2026-10-31 (61 days left). C.R.S. 37-92-302(3): due by the last day of the second month following the filing month — computed, not legal advice; confirm with the water clerk.
All 1 filings, with excerpts
| Case | What it asks | County | Excerpt |
|---|---|---|---|
26CW3012
|
change of water right | RIO BLANCO | 26CW3012 Rio Blanco County. Application For Change of Water Right and Approval of Augmentation Plan. Applicant: Three Crown Ranch, LLC, Balcomb & Green, P.C., P.O. Drawer 790, Glenwood Springs, CO 81602, (970) 945-6546; balcombgreen.com. First Claim for Change… |
Active substitute water supply plans in this district
Temporary State Engineer approvals to divert out of priority (37-92-308 / 37-90-137). A structure operating under one behaves differently under a call than its decreed rights alone suggest — the priority tables above don't know about these; this list does. Source: DWR’s active-SWSP register, refreshed nightly.
| Plan | Type | Status | Expires | Structure | Documents |
|---|---|---|---|---|---|
| FRASER, TOWN OF - MARYVALE WELLS | 37-92-308(7) PLAN EMERGENCY | Approved | 2026-07-08 | — | plan file |
| COLD SPRINGS RANCH & GREENHOUSE | 37-92-308(5) PLANS LESS THAN 5 YEARS | Approved | 2027-07-31 | — | plan file |
| KATTENBURG PIT | 37-90-137(11) GRAVEL PIT PLAN | Approved | — | — | plan file |
| BYERS PEAK PROPERTIES, LLC | 37-92-308(5) PLANS LESS THAN 5 YEARS | Pending | — | — | plan file |
| RANCHES AT DEVILS THUMB 23CW3209 | 37-92-308(4) PLAN PENDING COURT APPLICATION | Additional Info Needed | — | — | plan file |
| WH CABINS LLC | 37-92-308(4) PLAN PENDING COURT APPLICATION | Finished Plan | — | — | plan file |
Call cascade
If a call were placed at a given seniority, which structures in this basin would be out of priority, and how much of their decreed rate would be curtailed? Computed from this basin's cached decrees.
What this does and doesn't model. Seniority arithmetic only: every right junior to the call is treated as curtailed. It does not model reach applicability — structures downstream of the calling point are not administered by it — and it applies no futile-call judgment. Read it as “who is junior to this date, and by how much,” not as a prediction of what the Division Engineer would actually order.
Pick a calling right
Real decrees from this basin, ordered by administration number — that is, by actual seniority. The years will look out of order, and that is correct: an administration number encodes the adjudication date as well as the appropriation date, so a right appropriated in 1970 can be administered ahead of one from 1950. A senior call curtails almost everything; a junior one curtails almost nothing.
Or enter an administration number directly
DWR administration numbers encode appropriation and adjudication dates; lower is more senior.